rtmidi, fix rtmidi.pc file (#7088)

media-libs/rtmidi/rtmidi-5.0.0.recipe

@@ -6,7 +6,7 @@ MIDI hardware and software."
 HOMEPAGE="https://www.music.mcgill.ca/~gary/rtmidi"
 COPYRIGHT="2003-2019 Gary P. Scavone"
 LICENSE="RtMidi"
-REVISION="2"
+REVISION="3"
 SOURCE_URI="https://github.com/theSTK/rtmidi/archive/refs/tags/$portVersion.tar.gz"
 CHECKSUM_SHA256="c7923e4eee82b06c007435892cb2c3212d9007fa482c6b718943bda71c02c5a7"
 SOURCE_DIR="rtmidi-$portVersion"
@@ -60,7 +60,10 @@ INSTALL()
 	make -C build install
 
 	prepareInstalledDevelLib librtmidi
-	fixPkgconfig
+	fixPkgconfig strict
+	sed -e 's,^includedir=\(.*\)include,includedir=${prefix}/'${relativeIncludeDir}',' \
+		-i $developLibDir/pkgconfig/rtmidi.pc
+
 
 	packageEntries devel \
 		$developDir \